The present invention relates to an apparatus for irradiating material by an electron beam. It applies to the irradiation of gases, liquids or solids. Gases are irradiated for chemical uses or for sterilization purposes. Liquids are also irradiated for chemical or food uses (sterilization of fruit juices, milk, water, etc.). Solids are irradiated for chemical uses (polymerization), medical uses (sterilization, food uses (irradiation of grain, fruit, potatoes, vegetables, etc.), genetic purposes (irradiation of seed, insects, etc.).
Various apparatuses are known for the irradiation of matter by an electron beam. One of these apparatuses supplies an electron beam in a plane passing through an exit window closed by a thin metal diaphragm. It belongs to an enclosure in which a vacuum has been formed and in which is located an electron gun, which emits a very flat, very long beam. This window can have a length of two metres for a width of a few centimeters. The displacement of the electrons must be perpendicular to the window surface, so as to traverse the same under optimum conditions.
It is possible to produce a planar electron beam from a punctiform electron beam which, as a result of a scanning system, is given an alternating linear movement in front of the window. The main disadvantage of an apparatus of this type is that of requiring the use of a scanning system and of limiting the utilization of electrons in a linear zone close to the window.
Of late electron accelerators have been designed, which make it possible to directly accelerate the electrons of a laminar beam by using either electron guns in which the electron source is constituted by a very long filament, or plasma devices in which the electrons are obtained by secondary emission from ions emanating from a filamentary anode.
These different apparatuses making it possible to obtain a planar electron beam suffer from several disadvantages. In the scanning apparatus, for the purpose of limiting the incidence of the electrons at the ends of the window, it is necessary to construct equipment having prohibitive overall dimensions. In apparatuses using electron guns and having a very long filament, it is difficult to replace the emissive filaments when they have deteriorated. In plasma devices it is difficult to obtain a uniform beam and consequently a uniform irradiation. These devices are also complex and costly.